Rain­wa­ter sug­ges­tions

Having de­pended on rain­wa­ter for many years I think there are bet­ter ways to im­prove the qual­ity of wa­ter cap­tured from a roof with­out buy­ing a range of off-the-shelf prod­ucts that cost quite a bit of money (The Shed, Is­sue No. 77).

Nor­mally, if it’s all of the roof wa­ter be­ing cap­tured, the down­pipes link up to one 100mm di­am­e­ter pipe which will ei­ther sur­round the house un­der­ground or per­haps run through the crawl space. This pipe feeds up the side of the tank and into the in­let. The sim­plest way to en­sure the first flush is di­verted is to sim­ply in­stall a di­ver­sion valve in the pipe as seen in the pic­ture of our tank. All I do is leave the valve open so if there’s just a small shower the wa­ter doesn’t go into the tank — dur­ing sum­mer that’s most of the time. I keep an eye on the weather fore­cast and after a bit of rain I go out and shut the valve. It sounds like a has­sle but I don’t find it is. It’s just part of be­ing aware of the weather. The same idea could be used if it’s only one down­pipe be­ing tapped into.

An­other tip is to make sure the waste pipe from the valve is a loose fit so it can eas­ily be re­moved and the cap of the di­ver­sion fit­ting can be un­screwed. I do this from time to time to clean larger bits of crap that block the out­let. This would not be nec­es­sary if a rain head or some sort of gut­ter guard is used, which is what I would have next time.

I would also put the di­ver­sion valve lower down the side of the tank and use a much big­ger one so all the wa­ter that sits in the pipes around the house can be flushed out from time to time. As for the calmed in­let and float­ing out­let shown in your il­lus­tra­tion, th­ese seem un­nec­es­sary if the first flush is di­verted, plus if you need to get into the tank to at­tach them they would be very dif­fi­cult to in­stall.

Fi­nally, I wouldn’t in­stall the tank siphon the way it is shown — it looks very likely to drain the whole tank.

Carey Hablous

Via email

Thanks for your email, Carey. Most of the prod­ucts men­tioned can be eas­ily made by any DIYer — you don’t have to pur­chase the kits. The siphon will not empty your tank — it has a hole to break the siphon once the wa­ter level gets to a nor­mal level. The real ad­van­tage of the siphon is sim­ply to take ad­van­tage of the fact that you will have to spill wa­ter any­way, so why not use it to make sure that the waste wa­ter comes from the base of the tank, where most of the sludge will be, not from the fresh in­put? — Jude Wood­side, Tech­ni­cal Editor